1. Field of the Invention
The present invention relates to a temperature sensor utilizing a dielectric body which has its dielectric constant varying depending on the variations of temperature.
2. Description of the Prior Art
Temperature sensors have been used in many electric home appliances such as refrigerators, air-conditioners, electric rice-cookers and others. The temperature sensor is adapted to detect and control the temperature in the electric home appliance.
Such temperature sensors includes a thermocouple type sensor adapted to generate an electromotive force corresponding to a difference between a reference temperature and a detected temperature and a platinum resistor or thermistor type sensor adapted to detect a varied temperature as a change in the resistance.
The thermocouple type sensor must have a certain amplifier since the electromotive force produced from the difference in temperature is very small. This means that the entire construction is more complicated and increased in manufacturing cost.
Although the platinum resistor type sensor can detect the temperature with very improved accuracy, it has a disadvantage in that the manufacturing cost thereof is correspondingly increased. The conventional electric home appliances do not require such an accuracy as provided by the platinum resistor type sensor and rather desire the reduction of price with a relatively reduced accuracy.
Since the thermistor type sensor has a relatively high accuracy of temperature detection with a relatively low manufacturing cost, it has been broadly used various appliances. However, the thermistor type sensor has a problem when its output detection signal is processed by the use of the micro-computer.
With the recent development of the micro-computer, it is progressively increased that the micro-computer receives and processes data from the temperature sensor. In such a case, since the output signals of the thermistor are generally provided as analog voltage signals, these analog signals must be converted into digital signals by a A/D converter prior to processing at the micro-computer. This means that the signal processing operation becomes more complicated.
Noises may be frequently included in the analog signal system from the thermistor to the A/D converter to degrade S/N ratio.